The invention refers to a steam pressure cooker, and in particular to pressure relief valves in such steam pressure cookers.
A known steam pressure cooker is illustrated in European patent No. 0 008 465. In the case of the known steam pressure cooker, the pressure relief valve is accommodated in a housing together with a tappet for indicating the pressure. The housing extends with an external thread member through an opening in the lid and is held on the inner side of said lid with the aid of a screw-fastened nut. A valve cap is screwed onto the valve housing on the outer side of the steam pressure cooker, and the distance between said valve cap and the lid can be increased or reduced by the user. In the interior of the valve cap there is provided a spring abutment for a spring, the other side of said spring resting on the valve body for the pressure relief valve and pressing said valve body against its valve seat. Hence, the response pressure for the pressure relief valve can be adjusted by screwing the valve cap upwards or downwards. Within a specific area, the pressure relief valve occupies its operative position in which the spring tension is greater than the desired steam pressure occurring in the interior of the cooking vessel during normal cooking processes. The valve cap can, however, be screwed upwards into a steam-discharge position in which the spring tension is increasingly reduced to values below the steam pressure in the interior of the cooking vessel. This permits a rapid discharge of steam so that the lid can be opened. For the purpose of cleaning, the nut must be screwed off and the entire valve housing must be removed from the lid. For making the valve seat then accessible and for cleaning it, it is additionally necessary to screw off the valve cap and to disassemble the pressure relief valve into its component parts, and this cannot be done without the risk of losing individual components. Moreover, the user always has to pay attention to the fact that all the individual parts have to be reinserted into the housing in the correct sequence and at the correct location and that the valve housing has to be fixedly connected to the lid with the aid of the nut. This, however, makes the cleaning process of the valve housing very complicated so that thorough cleaning will probably not be carried out a sufficient number of times. In this case, however, it may easily happen that, due to particles of food adhering to the valve or due to a layer of grease, the pressure relief valve will no longer function in a satisfactory manner.
U.S. Pat. No. 2,614,724 discloses a steam pressure cooker in the case of which the load acting on the pressure relief valve is not applied by means of a spring but by means of weight plates. The valve body is held and guided by the lower weight plate. The valve seat is located in the lid. The weight plates are secured to the lid such that they can be pivoted independently of one another so that they can be pivoted upwards individually for providing a possibility of varying the response pressure of the pressure relief valve in response to the desired pressure within the cooking vessel. Although cleaning can be effected in a comparatively easy manner in this case, the cooking vessel, when in operation, cannot be handled without danger of accident. For example, all weight plates have to be pivoted upwards for allowing a discharge of steam before the locking mechanism is disengaged so that the lid can be opened. When the weight plates, which are normally hot, are raised, a sharp, hot steam jet is discharged from the valve seat in the lid immediately adjacent the user's hand, and this steam jet will almost inevitably impinge on the user's hand.
The weight plates will inevitably increase the weight of the lid substantially so that it is perhaps no longer possible to hold said lid with only one hand. When the size of the valve opening is kept small so as to save weight, the risk of clogging will increase.
Hence, the present invention is based on the task of providing a steam pressure cooker of the above-mentioned type, which is provided with a lightweight, handy lid, which has a simple structural design and is easy to operate and easy to clean, and in the case of which the danger of accident is reduced to a very large extent.
This task is solved by claim 1 which provides a spring abutment upon a pivotable flap at which the valve body is guided and supported, and a control means which, with the aid of the flap, can be pivoted from the operative position to the steam discharge position, as well as to the cleaning position.
On the basis of the structural design according to the application, it is achieved that there is no longer any necessity of disassembling and re-assembling the pressure relief valve for the purpose of cleaning. Notwithstanding this, all parts of the pressure relief valve are freely accessible, and all adhering particles of food which may impair adequate functioning of the pressure relief valve can be removed by hand or under a jet of water. On the basis of the arrangement of the control means and the special steam-discharge position, it is additionally achieved that, on the one hand, the steam can escape comparatively slowly so that a sharp, hot jet will not be formed. On the other hand, the user's hand is positioned at the greatest possible distance from the location at which the hot steam escapes. Moreover, there is no longer any necessity of touching any hot part of the cooking vessel.
On the basis of the embodiment according to claim 2, the accessibility for cleaning purposes is still further improved by providing that, in the cleaning position, the valve body is pivoted away from the valve seat arranged on the lid.
Claim 3 describes a particularly advantageous structural design of the control means, in that the control means includes a control member which acts on the flap and which is adapted to be moved with the aid of an actuating means to be operated by the user.
Claim 4 describes a first example of an actuating means, which can be operated by hand in a particularly simple and easy manner in that the actuating means is a slide knob connected to the control member.
The arrangement of the pivot pin of the flap according to claim 5, in which the pivot pin of the flap is arranged on the side of the pressure relief valve facing the control means, permitting a compact construction.
The embodiments according to claims 6 to 8 are easy to manufacture and, notwithstanding this, they function in a reliable manner.
Claim 9 describes a first example of the arrangement of the guide surface.
The structural design according to claim 10 facilitates actuation.
Claims 11 and 12 describe a first example of pivoting the flap by means of the control member.
Claims 13 to 15 describe a second example indicating how the control member can move the flap.
Claims 16 and 17 describe a third example indicating how the control member can move the flap.
Claims 18 to 20 describe a fourth example, indicating how the control member can move the flap, in which the control member is connected to the flap via a joint arranged in a spaced relationship with the pivot pin.
Claims 21 to 23 describe a fifth example in the case of which the pivot pin of the flap is arranged at the pressure relief valve side facing away from the control means. It is thus possible to provide the control means with an extremely uncomplicated and very robust structural design.
Claims 24 and 25 refer to a sixth example in the case of which the flap is pivoted via a push button, which acts essentially perpendicularly on the control member.
The control means, which is accommodated in the interior of one handle half according to claim 26, is thus protected against damage to a very large extent.
In connection with a sliding block engaging a groove in accordance with claim 27, a rail adapted to be displaced with the aid of the actuating means is provided in a particularly advantageous manner, said rail guaranteeing (claims 27 to 30) that the flap cannot be moved to the cleaning position as long as the lid is still positioned on the cooking vessel. It is thus guaranteed in a simple manner that the pressure relief valve is not fully opened unintentionally.
An additional safety means preventing incorrect operation is described in claim 31. In this way, it is guaranteed that the pressure relief valve can only be moved to its operative position when the lid is located on the cooking vessel in a position predetermined for cooking. It follows that internal pressure cannot build up when the lid is not positioned correctly.
Claims 32 to 37 describe alternative structural designs of the locking member.
The structural designs according to claims 38 to 40 facilitate the closing of the lid, since, on the basis of said structural designs, the locking member blocking the groove can be raised more easily from its locking position.
In accordance with claim 41 different response pressures for the pressure relief function can be adjusted, for example by pretensioning the spring of the pressure relief valve for various response pressures.